Dementia rates have fallen in a number of high-income countries over the past 25 years. Researchers have hypothesized that the decline reflects rising levels of educational attainment, a critical indicator of cognitive reserve which may account for individuals? susceptibility to Alzheimer?s disease-related pathology. Technological and socioeconomic advances have disproportionately allowed well-educated persons to maximize the potential for a longer, healthier life due to healthier jobs and lifestyles, early adoption of health enhancing technologies, and improved control over disease risks (e.g., hypertension and diabetes)?all potential promoters of cognitive reserve. The ability of those with advanced education to garner health advantages is also accelerating, potentially widening the educational gradient in AD over time. Given the critical role of education in influencing AD and education?s centrality in the life course, this study evaluates the influence of education on cognitive health in the context of the life-course development and maintenance of cognitive reserve. The study is based on the Health and Retirement Study, 1998-2018, and represents the experiences of persons 65 years of age and older in the United States. The study is organized around two aims. A1: Because early-life conditions set in motion adult achievement processes and exposures-all AD risk factors, largely through the critical life experience of education, how do early-life conditions and education combine to influence dementia? We are interested in two basic issues. First, when early-life conditions are statistically controlled, what are the net consequences of education for dementia, and how have these associations changed over the 20-year period? Second, to the extent that both early-life conditions and education independently influence dementia, how do these factors combine to influence dementia across the period? A2. How sensitive are the effects of education, net of early life conditions, to the inclusion of major adult pathways also indicative of cognitive reserve? Has the sensitivity changed over time? Several major pathways will be examined in this study?socioeconomic achievement, health behaviors (smoking, heavy alcohol use and physical activity, and disease risk factors (e.g., CVD, depressive symptoms, and diabetes). Dramatic changes have occurred in all of these spheres that will inform our understanding the potentially changing pathways between education, adult AD-risk factors and cognitive health. At its core, this study is designed to inform our understanding of how education-a crucial AD risk factor-influences the cognitive health of older Americans. We use an approach in which education is embedded in the life course and assess the potentially complex ways life-course factors may combine to influence cognitive health; this provides an important window into the life-course origins of AD-related pathology. In addition, we recognize the enormous racial divide in AD risk, and we explicitly attend to the ways in which education may differentially benefit the cognitive health of blacks and whites in the context of the life course.